24/08/2014 19:11 BST | Updated 24/10/2014 06:59 BST

Why We Shouldn't Lower the Age For Cervical Screening

Hearing of the death of Dawn Weston recently was saddening, but as a doctor, and gynaecologist-in-the-making it also prompted me to think again about whether we should in fact lower the age threshold for cervical screening. Every doctor takes a vow to 'do no harm'. Having considered the evidence, I firmly believe that to lower the age of cervical screening would do more harm than good, in the younger age group.

Cervical screening, based around 'The smear test' has been around since the 80's and is not aimed at diagnosing cancer, but at detecting abnormal cells that may turn into cancer in the future. These cells can then be removed, and the screening program has been shown to reduce cases of cervical cancer by 75% in this country. Not all abnormal cells need removing; the younger the woman and the milder the changes, and the more likely they are to spontaneously regress with time. The reason for this is due to the natural history of the human papilloma virus (HPV), which we know to be the causative agent of cervical cancer. HPV is a virus that almost every sexually active woman is exposed to during her lifetime. The peak age of infection is 20 years.

Makes sense to start screening then? No. Because 90% of women clear the infection within two years. During that time, minor abnormalities may be detectable on a smear test, but once the body has cleared the infection, the abnormal cells of the cervix will go back to normal. A small proportion of women are unable to clear the HPV infection, and these are the group that goes on to have a higher degree of abnormality on the cervix. Even in this group, only a tiny proportion would go on to develop a cancer, and this takes around 10-20 years from the original HPV infection. Unfortunately rare cases do exist, where this transition must be accelerated, but we are talking about screening the masses. That is the most important fact when deciding when to start screening. By starting screening at 25, we are giving the body chance to develop HPV infection and clear it, so that we only detect significant, persistent changes, rather than transient changes that are unlikely to ever progress to cancer.

An excellent study of cervical screening in England and Wales, showed that if we started screening at 20, rather than 25, we would need to do up to 40,000 smear tests and treat up to 900 women, in order to prevent one case of cervical cancer. The treatment, although simple is not without risks. Most notably, it may results in an increased risk of late miscarriage and premature birth in a future pregnancy. These risks are may in fact be greater than the risk of developing cervical cancer if left untreated. Given the large number of tests and hospital appointments required, to lower the age of screening is not a financially viable decision, particularly with a national healthcare system busting at the seams.

In addition, an abnormal smear test can cause a tremendous degree of anxiety. Every week I speak to countless women who have been referred to the colposcopy clinic with an abnormal smear result. They have been terrified since they received the appointment two to four weeks ago, and will continue to be terrified until they receive the results of further tests, in the following two to four weeks explaining that everything is absolutely fine. Is it ethical to put such a huge volume of women in this position, in order to pick up maybe a couple of cases of serious disease?

In spite of this information, there may in fact be some young women who do require a smear test, or referral to a gynaecologist. Any women with symptoms such as abnormal vaginal bleeding, abnormal discharge, or pelvic pain should go to see their GP. A good doctor will be able to have a frank discussion about why you do, or do not need a smear test or onward referral. A smear test is a screening test, and is by no means a substitute for a thorough medical assessment which may diagnose numerous other causes for the symptoms, which are much more common than cervical cancer, particularly in the younger age group.

Smear testing will continue to save the lives of hundreds and thousands of women in this country. But in younger women, the evidence quite clearly suggests the minimal benefit to their health is outweighed by the unacceptable risks.